1. Create a Firebase project if you don’t have one from here
   

2. Enter your app name and click continue

Next step also click on continue

3. In third and last step select your account and click on Create Project:

4. Please follow below steps in screenshots:

Now you have successfully configured login with OTP/SMS with Firebase for your app.

Add SHA-256 fingerprint in your Firebase app so from the Settings Page of the Firebase console. Don’t forget to download and replace the latest google-services.json file